This invention relates to an electronically controlled distributor type fuel injection pump adapted for use in internal combustion engines, particularly in diesel engines.
Among conventional distributor type fuel injection pumps, an electronically controlled type is known, e.g. from Japanese Provisional Patent Publication (KOKAI) No. 57-91366, wherein the fuel injection quantity and injection timing of the fuel injection pump is electrically controlled. According to this proposed type, a governor, an injection timing control device and a control sleeve are omitted from the fuel injection pump, but a single solenoid valve is employed instead for controlling the fuel injection quantity and the injection timing through its opening and closing actions, in such a manner that the fuel injection is initiated upon opening of the solenoid valve and terminated upon closing of same. Therefore, the solenoid valve is required to have high responsiveness enough to fully exhibit these functions. However, even highly responsive solenoid valves cannot satisfactorily exhibit their responsiveness at the start of the engine in cold weather such as in winter when the fuel is low in temperature and accordingly high in viscosity, and in addition the supply voltage from the battery is low, which can cause inconveniences such as deteriorated startability of the engine.
Further, in these electronically controlled fuel injection pumps, when the solenoid valves per se or the control means for driving them fail or malfunction, proper operation of the solenoid valves cannot be performed, resulting in interruption of the fuel injection and accordingly stoppage of the engine operation.